This invention relates generally to opthalmosurgical devices, and more particularly to a device used for the introduction of a corneal implant into the cornea of a mammalian eye. In general, such implants are used to adjust corneal curvature and correct vision abnormalities such as hyperopia.
Anomalies in the overall shape of the eye can cause visual disorders. Hyperopia ("farsightedness") occurs when the front-to-back distance in the eyeball is too short. In such a case, parallel rays originating greater than 20 feet from the eye focus behind the retina. Although minor amounts of hyperopia can be resolved in the human eye by a muscular action known as "accommodation", aging often compromises the ability of the eye to adequately accommodate. In contrast, when the front-to-back distance of the eyeball is too long, myopia ("nearsightedness") occurs and the focus of parallel rays entering the eye occurs in front of the retina. Astigmatism is a condition which occurs when the parallel rays of light do not focus to a single point within the eye, but rather have a variable focus due to the fact that the cornea refracts light in a different meridian at different distances. Some degree of astigmatism is normal, but where it is pronounced, the astigmatism must be corrected.
Hyperopia, myopia, and astigmatism are usually corrected by glasses or contact lenses. Surgical methods for the correction of such disorders are known. Such methods include radial keratotomy (see, e.g., U.S. Pat. Nos. 4,815,463 and 4,688,570) and laser corneal ablation (see, e.g., U.S. Pat. No. 4,941,093).
Another method for correcting these disorders is through the implantation of polymeric implants into the cornea instromal space to change the curvature of the cornea. Devices currently available for introducing the implants into the eye include standard forceps which are used to grasp the implant and manipulate it into an incision formed in the eye. The implant grasping surfaces of the forceps are typically flat or formed with small ridges, and do not conform to the specific shape of the implant. This makes it difficult to grasp the relatively small implants. Once the implant is picked up by the forceps, it is often difficult to retain the implant within the grasp of the forceps. If the implant is dropped it has to be sterilized again prior to use. These forceps are also not well suited for insertion of the implant into the incision. Because the forceps are designed to grasp the implant only along its sides to allow the forceps to release and regrasp the implant, the implant often backs out of the forceps during insertion into the eye. This also makes it difficult to push and manipulate the implant once it is partially inserted into the incision.
Furthermore, these forceps are configured for holding, and introducing into the eye only one implant at a time. This requires reloading and repositioning of the forceps prior to inserting each implant into the eye. Since the forceps are not designed for storage of the implants, the implants cannot be preloaded and packaged with the forceps.